A Study Of Photoresponse For Cadmium Telluride Modified By VIA Compounds To Glutathione

Biothiols（Glutathione,GSH）,play a crucial role in the detoxification of foreign substances.As one of the most abundant antioxidant biothiols in cells,GSH is widely used in medicine and food.Considering the importance of GSH in food science,pharmacy and clinical practice,developing the methods that can monitor the levels of GSH is of great significance and urgently required.A fluorescence sensor is a powerful tool for the detection of GSH because of its high sensitivity and selectivity.However,the rapid separation and recombination of electron-hole pairs in CdTe semiconductor results in poor fluorescence response.To solve this problem,researchers have prepared semiconductor materials to suppress the recombination of electron-hole pairs and improve the photoelectric performance.Therefore,in this thesis,the photoresponse of CdTe interface modified by VIA group compounds were studied,and the photoresponse phenomenon and mechanism of glutathione（GSH）were introduced in detail.The research contents are as follows:（1）The preparation and properties of CdTe.CdTe nanoparticles were prepared by coprecipitation reduction method at different mole ratio,water bath temperature,water bath time and sintering temperature.XRD and SEM results showed that the formation rate of CdTe and the crystallinity were increased with the increase of water bath temperature.The average particle size of CdTe was 500～900 nm.Finally,the effects of p H and GSH concentration of PBS buffer solution on the fluorescence intensity of CdTe were studied by fluorescence spectroscopy.Finally,the effects of p H of PBS buffer solution and GSH concentration on the fluorescence intensity of CdTe were studied by fluorescence spectroscopy.The results revealed that the fluorescence intensity of CdTe increased with the increase of GSH concentration,which conformed to the equation of y=700.77+25.90ln（x-0.01）,R²=0.9812.Therefore,CdTe played an important role in the fluorescence response of GSH.（2）The synthesis and photoelectric properties of CdTe/MX（M=Zn,Cd,Sb,Bi;X=Te,Se,S,O）nanocomposites.CdTe/MX nanocomposites were synthesized by low temperature liquid phase method,and the photoresponse of GSH at CdTe/MX interface was studied.Through the detailed characterization of the structure and morphology,CdTe/MX nanoparticles were obtained with average particle size of 100～200 nm,uniform distribution and well photoelectric properties.GSH exhibited fluorescence enhancement and fluorescence quenching at the CdTe/MX interface.When CdTe/MX composites formed the conduction band alignment,the addition of GSH showed fluorescence enhancement;When CdTe/MX composites formed the valence band alignment,the addition of GSH showed fluorescence quenching.The quenching constants were 1.8×10²,6.6×10²,2.3×10²,1.3×10²and 8.2×10²,respectively.The detection limit of CdTe/Bi₂S₃ for GSH was 1μM.The photocurrent of FTO/CdTe/Sb₂Se₃ and FTO/CdTe/CdO electrodes modified by GSH increased,while the photocurrent of FTO/CdTe/Bi₂S₃ electrode decreased by 84%.The results showed that the interaction between GSH and CdTe/MX was mainly caused by-SH,and the interface electron transfer was the main mechanism of photoelectric response.（3）The synthesis and photoelectric properties of CdTe/CdS/MX（M=Zn,Bi;X=Te,Se,S,O）nanocomposites.CdTe/CdS/MX nanocomposites were synthesized by liquid phase method.And the photoresponse of GSH and CdTe/CdS/MX was studied.The CdTe/CdS heterojunction enhanced the fluorescence intensity of the material,reduced the electron-transfer resistance of CdTe/CdS/MX,and achieved fast electron transfer rate.The results of FL,EIS,CV and I-T showed that GSH has high photoresponse to CdTe/CdS/Zn Te,CdTe/CdS/Zn Se,CdTe/CdS/Bi₂Se₃and CdTe/CdS/Bi₂S₃.CdTe/CdS/Bi₂O₃ modified by GSH showed fluorescence quenching with the quenching constant of 3.1×10^-2.The detection limit of GSH was 8μM for CdTe/CdS/Bi₂O₃ in the range of 0.025～0.6 mmol·L^-1.Therefore,the mechanism of electron transfer and band gap alignment are described in the interface of CdTe nanocomposites in this thesis,explaining the photoresponse of GSH to CdTe/MX.This provides theoretical reference and new technical route for CdTe nanocomposites in the detection of biological mercaptan.